This invention relates to a fluid-tight electrical coupling system for implantable medical devices, such as implantable defibrillators.
Great strides are presently being made to develop an automatic, fully implantable defibrillator. See, for example, U.S. Pat. Nos. Re. 27,652 and Re. 27,757, where the first concept of the automatic implantable ventricular defibrllator is described. Recent advances have also been made in enhancing the reliability of fibrillation detectors. In this latter regard, see co-pending U.S. patent applications Ser. Nos. 878,005 and 878,006, each filed on Feb. 15, 1978 and now U.S. Pat. Nos. 4,202,340 and 4,184,493 respectively. Furthermore, as outlined in co-pending U.S. Pat. application Ser. No. 801,300, filed on May 27, 1977, and now U.S. Pat. No. 4,164,946, steps have been taken to improve the reliability of the implanted defibrillator by the provision of circuitry which interrogates the implanted electronics to verify proper operation before a defibrillating shock is delivered.
In co-pending U.S. Pat. application Ser. No. 53,797, filed on July 2, 1979, entitled "Implantable Defibrillator Package" incorporated herein by reference, an implantable defibrillator package is disclosed having an implantable casing, or housing, and a lid portion hermetically sealed to the casing to form a hermetic seal. An epoxy housing is provided on the lid portion for receiving electrode leads having plugs, the electrodes leads also implantable in the body of a recipient. Terminal blocks within the epoxy housing receive portions of the plugs, and electrical conductors interconnect the terminal blocks with feed-through electrical terminal pins extending into the epoxy housing, and through the lid portion, for electrical communication with circuitry disposed in the casing.
It is highly desirable that the plugs be physically secure within the terminal block, and yet be fully explantable for replacement. Moreover, fluid seepage into the terminal block area must be prevented to ensure corrosion-free contact between the terminal block and the plug, thus assuring electrical integrity of the connection and easy removal of the plug from the terminal block for replacement.
It is thus essential that any openings in the epoxy housing be sealed to prevent leakage into the housing interior. Sealing elements are known which included caps which either snap into the device to be sealed or have a bayonet-type connection.
The present invention is directed toward filling the needs expressed above.